Fabrication and characterization of high-k dielectric nickel titanate thin films using a modified sol-gel method

This research produced high-quality, single-phase nickel titanate (NiTiO₃) thin films, a high-k material for gate dielectrics, by a modified sol-gel method. The precursor was prepared by reactions of nickel acetate tetrahydrate and titanium isopropoxide in 2-methoxyethanol with a 1:1 ratio of Ni/Ti in the solution. After coating, the films were post-heat treated between 500° and 900°C. X-ray diffraction indicated that the films deposited at and above 600°C were single-phase nickel titanate. X-ray photoelectron spectra of a typical thin film revealed that the binding energies of Ni 2p_3/2 and Ti 2p_3/2 electrons were 855.2 and 457.7 eV, respectively. Raman spectra showed eight absorptions between 200 and 800 cm^-1. Scanning electron microscope images showed smooth surfaces. Findings showed the dielectric constant of the NiTiO₃ film to be 41.36 by capacitance-voltage analysis. The results show that single-phase NiTiO₃ film can be prepared by the sol-gel spin coating method and then heat-treated at 600°C.